这个是个4个数码管显示时间的程序，用AT89S52实现，用四个按键控制，能实现时钟显示，闹钟定时，倒计时三项功能，电路图很简单。-This is a 4 digital tube display time-consuming procedures, use AT89S52 realize, with four buttons control, can realize the clock display, alarm clock, timer, countdown to the three functions, circuit is very simple.